In systems, such as telecommunications systems, it is often necessary to exchange circuit packs or cards while the remaining circuit packs or cards are in an operating state. If such a circuit pack or card presents a capacitive load to the power supply line(s), the enabling of the circuit will place a capacitive load on the power supply line(s) that may adversely affect the operation of the operating circuits. To mitigate this problem such circuit packs or cards are often provided with decoupling capacitors on the voltage supply inputs. Chokes may also be installed to reduce the effect of these discharge transients.
A diode in series with the load would allow charging the decoupling capacitor and prevent discharging during a dip in the power supply voltage, but may introduce an unacceptably large voltage drop for most applications.